Publications

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2026

Variational early fault-tolerant quantum computing workflow

Image credit: Figure 1, Meyer et al., QCE 2026 · © 2026 IEEE · reuse terms

Variational Early Fault-Tolerant Quantum Computing

Nico Meyer, Christopher Mutschler, Dominik Seuß, Andreas Maier, Daniel D. Scherer.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 2, pp. 672–673, September 2026 (proceedings to appear).

This short conference version of “Learning Logical Operations for Arbitrary Quantum Error Correction Codes” describes VarEFTQC, a method for designing noise-adapted quantum codes together with their logical gates. It demonstrates a five-qubit non-additive code with a shallow universal gate set tailored to structured depolarizing noise.

Schematic overview of learning logical operations for quantum error-correcting codes

Image credit: Figure 1, Meyer et al., Physical Review A (2026) · © 2026 American Physical Society · reuse terms

Learning Logical Operations for Arbitrary Quantum Error Correction Codes

Nico Meyer, Christopher Mutschler, Dominik Seuß, Andreas Maier, Daniel D. Scherer.

Physical Review A 114, 032424, 2026.

A learning-based framework finds physical implementations of logical gates directly from an encoding circuit, including for non-additive error-correcting codes. It also jointly optimizes encodings and logical operations for specific noise and gate-set requirements, with demonstrations on standard codes and an accompanying software library.

Schematic of noise-aware code concatenation

Image credit: Figure 1, Meyer et al., QCE 2026 · © 2026 IEEE · reuse terms

Learning to Concatenate Quantum Codes

Nico Meyer, Christopher Mutschler, Dominik Seuß, Andreas Maier, Daniel D. Scherer.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 1, pp. 2838–2844, September 2026 (proceedings to appear; linked preprint).

This work adapts each level of quantum-code concatenation to the effective noise left by the preceding level. Learned, small encoders handle structured noise before conventional codes take over; simulations show that this combination can reach target logical error rates with substantially fewer physical qubits.

Three-stage compilation of a logical Clifford circuit

Image credit: Figure 4, Popov et al., qCCL 2026 · © 2026 IEEE · reuse terms

Optimized Compilation of Logical Clifford Circuits

Alexander Popov, Nico Meyer, Daniel D. Scherer, Guido Dietl.

IEEE International Conference on Quantum Control, Computing, and Learning (qCCL), vol. 1, pp. 1–6, July 2026.

Rather than compile logical Clifford circuits gate by gate, the paper examines larger circuit blocks for an error-detecting code family. It derives depth-efficient compilation patterns from small instances and reports lower simulated error rates for several circuit structures.

2025

Training noise-adapted quantum error correction encodings

Image credit: Figure 1, Meyer et al., QCE 2025 · © 2025 IEEE · reuse terms

Variational Quantum Error Correction

Nico Meyer, Christopher Mutschler, Andreas Maier, Daniel D. Scherer.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 2, pp. 456–457, September 2025.

This short conference version of “Learning Encodings by Maximizing State Distinguishability: Variational Quantum Error Correction” uses the distinguishability of noisy quantum states to train noise-adapted error-correcting codes. It compares the learned encodings with standard codes and includes proof-of-concept experiments on quantum hardware.

Noise-adapted quantum error correction encoding procedure

Image credit: Figure 1, Meyer et al., Quantum Science and Technology (2026) · © 2026 authors · CC BY 4.0

Learning Encodings by Maximizing State Distinguishability: Variational Quantum Error Correction

Nico Meyer, Christopher Mutschler, Andreas Maier, Daniel D. Scherer.

Quantum Science and Technology 11(4), 045036, 2026.

Maximizing the distinguishability of encoded states after noise provides a training objective for variational quantum error correction. The resulting noise-adapted codes can reduce resource demands relative to standard codes in the studied settings; proof-of-concept tests run on IBM and IQM hardware.

Figure 1: Decomposition of the BenchQC benchmarking workflow

Image credit: Figure 1, Geissler et al., Springer (2026) · arXiv v1 licensed CC BY 4.0

BenchQC – Scalable and modular benchmarking of industrial quantum computing applications

Florian Geissler, Eric Stopfer, Christian Ufrecht, Nico Meyer, Daniel D. Scherer, Friedrich Wagner, Johannes M. Oberreuter, Zao Chen, Alessandro Farace, Daria Gutina, Ulrich Schwenk, Kimberly Lange, Vanessa Junk, Thomas Husslein, Marvin Erdmann, Florian Kiwit, Benjamin Decker, Greshma Shaji, Etienne Granet, Henrik Dreyer, Theodora-Augustina Dragan, Jeanette Miriam Lorenz.

International Quantum Engineering Conference and Exhibition (QUEST-IS), Springer CCIS vol. 2743, pp. 207–216, December 2025 (linked preprint).

BenchQC develops an application-led framework for evaluating quantum solutions to industrial use cases. Using the open-source QUARK platform, it measures the full workflow from application to hardware and compares approaches to identify where quantum computing might offer practical value.

Comparison of sample complexities in quantum and classical reinforcement learning

Image credit: Figure 1, Meyer et al., ICML 2025 · © 2025 authors

Benchmarking Quantum Reinforcement Learning

Nico Meyer, Christian Ufrecht, George Yammine, Georgios Kontes, Christopher Mutschler, Daniel D. Scherer.

International Conference on Machine Learning (ICML), PMLR vol. 267, pp. 43934–43964, July 2025.

To compare quantum and classical reinforcement learning more reliably, the paper proposes statistical measures of sample complexity and outperformance. Experiments on a configurable benchmark question some earlier quantum-advantage claims while identifying more limited settings in which advantages may remain possible.

2024

Quantum circuit used as the regularized policy approximator

Image credit: Figure 1, Meyer et al., arXiv (2024) · © 2024 authors

Robustness and Generalization in Quantum Reinforcement Learning via Lipschitz Regularization

Nico Meyer, Julian Berberich, Christopher Mutschler, Daniel D. Scherer.

arXiv:2410.21117, 2024.

The RegQPG algorithm regularizes quantum policy-gradient training using Lipschitz bounds to improve robustness and generalization. A curriculum-learning variant is designed to avoid failures during training, and numerical experiments examine the benefits of both approaches.

Variational quantum policy iteration workflow

Image credit: Figure 1, Meyer et al., QCE 2024 · © 2024 IEEE · reuse terms

Warm-Start Variational Quantum Policy Iteration

Nico Meyer, Jakob Murauer, Alexander Popov, Christian Ufrecht, Axel Plinge, Christopher Mutschler, Daniel D. Scherer.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 1, pp. 1458–1466, September 2024.

Variational quantum policy iteration uses a quantum subroutine to solve the linear-system step of reinforcement-learning policy iteration. The warm-start version reduces resource overhead and is evaluated on a FrozenLake task involving a 256-by-256 linear system.

Variational linear-system solver results for loss and basis-state values

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Comprehensive Library of Variational LSE Solvers

Nico Meyer, Martin Röhn, Jakob Murauer, Axel Plinge, Christopher Mutschler, Daniel D. Scherer.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 2, pp. 1–4, September 2024.

The variational-lse-solver framework brings together implementations of variational quantum algorithms for linear systems and adds practical improvements. It provides a common interface for researchers developing and comparing end-to-end applications.

Runtime comparison of quantum machine-learning frameworks by qubit count

Image credit: Figure 1a, Meyer et al., QCE 2024 · © 2024 IEEE · reuse terms

Qiskit-Torch-Module: Fast Prototyping of Quantum Neural Networks

Nico Meyer, Christian Ufrecht, Maniraman Periyasamy, Axel Plinge, Christopher Mutschler, Daniel D. Scherer, Andreas Maier.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 1, pp. 817–823, September 2024.

Qiskit-Torch-Module connects Qiskit quantum neural networks with PyTorch for faster prototyping and training on a single machine. The reported benchmarks show large runtime improvements over comparable approaches while keeping integration with existing code straightforward.

2023

Comparison of optimizer mean-square errors across training epochs

Image credit: Figure 2, Wiedmann et al., QCE 2023 · © 2023 IEEE · reuse terms

An Empirical Comparison of Optimizers for Quantum ML with SPSA-based Gradients

Marco Wiedmann, Marc Hölle, Maniraman Periyasamy, Nico Meyer, Christian Ufrecht, Daniel D. Scherer, Axel Plinge, Christopher Mutschler.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 1, pp. 450–456, September 2023.

This study combines the low-cost gradient estimates of SPSA with conventional gradient-based optimizers for variational quantum circuits. In regression experiments, the hybrid method converges faster and more accurately than the compared alternatives, including under sampling and hardware noise.

Quantum natural policy-gradient training workflow

Image credit: Figure 1, Meyer et al., QCE 2023 · © 2023 IEEE · reuse terms

Quantum Natural Policy Gradients: Towards Sample-Efficient Reinforcement Learning

Nico Meyer, Daniel D. Scherer, Axel Plinge, Christopher Mutschler, Michael J. Hartmann.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 2, pp. 36–41, September 2023.

Quantum natural policy gradients use an efficient approximation of the quantum Fisher information matrix to train reinforcement-learning policies. The experiments report faster, more stable learning and lower sample requirements than first-order training, with an additional demonstration on a 12-qubit device.

2022

Variational quantum circuit and classical action-decoding workflow

Image credit: Figure 1, Meyer et al., ICML 2023 · © 2023 authors

Quantum Policy Gradient Algorithm with Optimized Action Decoding

Nico Meyer, Daniel D. Scherer, Axel Plinge, Christopher Mutschler, Michael J. Hartmann.

International Conference on Machine Learning (ICML), PMLR vol. 202, pp. 24592–24613, July 2023.

The paper improves quantum policy-gradient training by optimizing how measurements of a variational quantum circuit are decoded into actions. The method performs better across several benchmarks and enables a complete training run on a five-qubit quantum device.

Classification of approaches to quantum reinforcement learning

Image credit: Figure 1, Meyer et al., arXiv (2022) · © 2022 authors

A Survey on Quantum Reinforcement Learning

Nico Meyer, Christian Ufrecht, Maniraman Periyasamy, Daniel D. Scherer, Axel Plinge, Christopher Mutschler.

arXiv:2211.03464, 2022.

This survey organizes the quantum reinforcement-learning literature, covering both variational-circuit methods for current noisy devices and approaches that rely on future fault-tolerant hardware. It compares the assumptions and potential advantages of the different lines of research.

Incremental encoding of an image into quantum classifier circuits

Image credit: Figure 1, Periyasamy et al., QCE 2022 · © 2022 IEEE · reuse terms

Incremental Data-Uploading for Full-Quantum Classification

Maniraman Periyasamy, Nico Meyer, Christian Ufrecht, Daniel D. Scherer, Axel Plinge, Christopher Mutschler.

IEEE International Conference on Quantum Computing and Engineering (QCE), vol. 1, pp. 31–37, September 2022.

Incremental data uploading interleaves feature-encoding gates with trainable gates so high-dimensional data can enter a quantum classifier without costly preprocessing. Comparisons on MNIST and Fashion-MNIST assess classification accuracy and model expressivity against other encoding schemes.